Creating stem cells might get easier

A surprising study has found that a simple acid bath might turn cells in the body into stem cells that one day could be used for tissue repair and other medical treatments.

A surprising study has found that a simple acid bath might turn cells in the body into stem cells that one day could be used for tissue repair and other medical treatments.

The technique, performed only with cells from mice, might turn out to be a quicker and easier source of multipurpose stem cells than methods now in use.

“If reproducible in humans, this could be a paradigm changer,” said Dr. Robert Lanza, a stem-cell scientist who was not involved in the work. Lanza, chief scientific officer of the biotechnology company Advanced Cell Technology, said the technique also might make it easier to clone animals or even people, raising ethical questions.

The new technique was developed by researchers at the Riken Center for Developmental Biology in Kobe, Japan, and at Brigham and Women’s Hospital and Harvard Medical School in Boston. Two papers by the researchers were published in the journal Nature yesterday.

Some experts expressed caution, saying that more must be known about the new approach.

“The existing methods are already quite advanced,” said Sheng Ding, a scientist at the University of California, San Francisco, and the affiliated Gladstone Institutes. “It’s too early to say this is better, safer or more practical.”

Certain stem cells can be easily grown in the laboratory and can turn into any type of cell in the body, which is called pluripotency. Researchers think these stem cells might be used one day to repair damaged cells and organs in the body, although experiments trying this in people are in early stages.

Initially, interest focused on embryonic stem cells, which could be obtained at first only by destroying human embryos.

Several years ago, Shinya Yamanaka of Kyoto University in Japan and other scientists developed a way to turn cells from the body, such as skin or blood cells, into stem cells, avoiding the need to destroy embryos. That work won Yamanaka a Nobel Prize.

These cells, called induced pluripotent stem cells, have an additional advantage over embryonic cells in that they can be created from a particular patient. Therefore, any cells derived from those stem cells and transplanted back into the patient would not be rejected by the immune system.

But creating those induced cells requires genetic changes to the cells, raising questions about whether they can be used for medical therapy.

The new technique does away with deliberate genetic changes. Instead, it involves subjecting specialized cells, such as blood or skin cells, to stress.

The researchers in Kobe and Boston tried stresses such as squeezing the cells but found that bathing the cells for half an hour in a mildly acidic solution seemed to work best. The technique worked for cells taken from organs of newborn mice, but the efficiency was highest using white blood cells.

The mice from which the cells were taken had been genetically engineered so their cells would glow green if Oct4, a gene associated with pluripotent cells, was active.

After the acid bath, the cells were grown in culture. Many cells died from the exposure to acid, but among those that survived, many were glowing green by the seventh day. The researchers called these STAP cells, for

stimulus-triggered acquisition of pluripotency.

To prove that the STAP cells could indeed turn into every cell type in the body, researchers injected the cells into early mice embryos. These embryos grew into mice, called chimeras, with cells derived from the STAP cells in all tissues of their bodies. The mice could reproduce and pass along the genetic characteristics from those cells.

The fact that descendants of the STAP cells could function in mice and their offspring also provided evidence that the cells were not abnormal.

“I was really surprised the first time we saw the chimeric mice,” said Haruko Obokata, a biologist at Riken and the lead author of the two papers in Nature. She had worked on the project for several years, first as a researcher at Brigham and Women’s under Dr. Charles A. Vacanti.

If the technique is to be used to treat patients, it would have to work with cells taken from adult humans, not newborn mice. Obokata said the technique worked using cells from older mice, but not as efficiently. She said researchers are testing whether the technique works with human cells.